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Theses

Réalisation d'un interféromètre de Martin-Puplett pour le développement d'une caméra bolométrique.

Abstract : The growing precision of scientific research into the evolution of the universe since the Big Bang involves the development of suitable sub-millimetric instruments which apply to observational cosmology, such as bolometric cameras. In this context, we see the need for an instrument which enables the determination of the spectral index and the optical characterization of a variety of materials making up the camera (detector array, filters, lenses, and so on...) using transmission or absorption measurements. Furthermore, due to the expansion of observational requirements, we also see the need to characterize these optical elements through polarized light and in different temperature conditions.

This thesis focused on the design, the realisation and the use of all the components of this instrumental chain. It is divided into three parts: the interferometer, the optical cryostat, and data gathering and processing. The Martin Puplett spectrometer is a Fourier transform millimetric spectrometer. It works along the same principles as a Michelson interferometer. A incident optical signal, modulated between a black body between 300K and 70K, is split into two beams by a beamsplitter. These two beams interfere after having travelled along a different distance. The signal transmitted by the system is polarized then red by a radiation detector, called a bolometer, which has been cooled down to a temperature of 2 K. The optical cryostat enables to cool down this bolometer thanks to liquid helium and to characterize the samples at a temperature of 4 K. Data acquisition is performed by the means of an electronic board which modulates the bolometer signal and amplifies the response. A graphic interface then enables to control and monitor its operation on the one hand, and to visualize and measure the spectral response on the other hand. It also enables to forward the data towards another data processing program which outputs spectral responses ranging from 50 to 300 GHz, with a resolution up to 1.3 GHz and an amplitude accuracy of 1 %. These responses can be obtained through seven different polarizations of the electronic field ranging from 0 to 90°. This instrument enabled the characterization of a variety of filters, lenses and bolometer matrix which will soon be mounted inside the bolometric camera.
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Contributor : Thomas Durand <>
Submitted on : Monday, October 22, 2007 - 6:19:32 PM
Last modification on : Thursday, November 19, 2020 - 1:01:01 PM
Long-term archiving on: : Sunday, April 11, 2010 - 11:35:18 PM

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  • HAL Id : tel-00181020, version 1

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Thomas Durand. Réalisation d'un interféromètre de Martin-Puplett pour le développement d'une caméra bolométrique.. Astrophysique [astro-ph]. Université Joseph-Fourier - Grenoble I, 2007. Français. ⟨tel-00181020⟩

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